Unusual feeding behaviour of Barn Swallow

“Barn Swallows (Hirundo rustica) are recognised aerial insectivores and their superb manoeuvrability aids this. Most authorities consider insects as the only item in their diet. Most of us would have seen them feeding low over the ground in open areas and often over a body of water. I find that a freshly ploughed/cut field and water are their favourite feeding environments.

“They are also known to pick items off the water surface but this behaviour is less commonly seen. Drinking, by scooping water while flying low over a body of fresh water, is often seen.

“I watched a flock of 30-40 Barn Swallows feed on items in the water of an ex-mining pool that is being used for fish farming. The flock consisted of adults with first year birds. Most were in some degree of moult and the majority had no T6 streamers (some had a single streamer, others unequal length streamers).

“I had difficult identifying the prey. There was no vegetation in the large ex-mining pool and much of the feeding was closer to the ‘shore’. There were some small items floating in the water but I could not reach them to determining what they were.

“Action was fast and I tried to capture some feeding episodes. I considered the unlikely possibility of fish-fry, but could not find any evidence for it in most of my images (except for one blur shot, above).

“I suspect that they are feeding on fish food that has been thrown into the pool. But having said that, the feeding technique puzzled me, and did not fit with floating fish food. The birds would fly over the surface, often banking hard and turning here and there, before plunging down. Many episodes were not productive.